TeamViewer - TeamViewer lets you establish a connection to any PC or server within just a few seconds.
Remmina - Remmina is a remote desktop client written in GTK+, aiming to be useful for system administrators and travellers, who need to work with lots of remote computers in front of either large monitors or tiny netbooks.
AnyDesk - AnyDesk is the world's most comfortable remote desktop application. Access all your programs, documents and files from anywhere, without having to entrust your data to a cloud service.
rdesktop - rdesktop is a free and open source remote desktop protocol client designed to make the users able to manage their PCs in a new way.
ConnectWise Control - ConnectWise Control is a mobile app that allows you to instantly connect with another system from anywhere with a connection to the internet. The software not only comes in a mobile app, but it has a desktop version as well for complete coverage.
KRDC - KRDC is the KDE Remote Desktop Client.